Cross-sectional and longitudinal associations between serum levels of high-sensitivity C-reactive protein, knee bone marrow lesions, and knee pain in patients with knee osteoarthritis

OBJECTIVE: To describe associations between serum high-sensitivity C-reactive protein (hsCRP), knee bone marrow lesions (BMLs), and knee pain, cross-sectionally and longitudinally, in patients with knee osteoarthritis (OA).

METHODS: Patients (n = 192) with symptomatic knee OA (mean age 63 years, range 50-79, women 53%) were assessed at baseline and after 24 months. Serum hsCRP was measured using enzyme-linked immunosorbent assay. Knee BMLs were scored using the modified Whole-Organ Magnetic Resonance Imaging (MRI) Score from T2-weighted fat-supressed fast spin-echo MRI. Knee pain was assessed using the Western Ontario and McMaster Universities Osteoarthritis Index.

RESULTS: Quartiles of baseline serum hsCRP were associated with the presence of knee BMLs (prevalence ratio 1.07 per quartile [95% confidence interval (95% CI) 1.00, 1.15]) and total knee pain scores (β 13.66 per quartile [95% CI 2.26, 25.07]) in multivariable analyses. Longitudinally, higher baseline hsCRP was associated with an increase in BML score (risk ratio 1.37 per quartile [95% CI 1.10, 1.70]), and change in hsCRP was positively associated with change in BML score (β 0.19 [95% CI 0.05, 0.34]) in adjusted analyses. Baseline hsCRP was not associated with change in total knee pain, but change in hsCRP was positively and significantly associated with change in total knee pain (β 4.71 [95% CI 0.48, 8.94]). This became nonsignificant after adjustment for changes in BML score.

CONCLUSION: In patients with knee OA, serum hsCRP is associated with knee BML scores and, to a lesser extent, pain both cross-sectionally and longitudinally, suggesting that inflammation is linked with BMLs and their associated pain.